Some widely used Internet services are inelastic such as VoIP (Voice over Internet Protocol), that is, data packets are generated frame-wise at a predominantly fixed frequency. Such services often require a small roundtrip time (RTT) in order to work well.
In mobile networks (e.g. IEEE 802.16 and 3rd Generation Partnership Project (3GPP)), a scheduler in the base station distributes the transmission capacity “fairly” between different data transmission flows or at least in such a manner that given needs of given occurring user entities can be served in accordance with agreed service level requirements. At the same time, the scheduler typically aims to utilize the transmission capacity in a way so that the “total transmissions” in the network can be maximized. This maximization of total transmissions typically involves delaying individual transmissions to suitable transmissions instances. Hence, scheduling involves that the available bandwidth is utilized in an optimized way such that a majority of users of the system are served according to agreed quality of service requirements.
A low latency requirement for a given traffic flow, takes up a high “transmission capacity”, since the flexibility for scheduling concurrent traffic flows is diminished. For wireless systems, where channel conditions typically vary substantially over time, e.g. due to the changing location for mobile stations, a large allowable delay, i.e. the time from a packet is received from a higher order equipment until the packet is transmitted to the mobile station, is preferred.
A VoIP service is often routed over several nodes where some nodes may use wireless transmissions. In order to ensure reasonable round trip times for e.g. VoIP services, the delay for each individual VoIP packet is typically set to a predefined maximum allowable value in each node.
The low round trip time (RTT) requirements for VoIP services imply that transmission capacity must be dedicated for such wireless transmissions. Since a VoIP session may be routed over several nodes, each node must comply with a predefined allowable maximum latency in order to guarantee a low total RTT.
In many prior art systems, latency requirements imply a negative toll on the total capacity of individual nodes and of the system in which the nodes are comprised.